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Under coherent interactions, particles undergo correlated collisions with the crystal lattice and their motion result in confinement in the fields of atomic planes, i.e. particle channeling. Other than coherently interacting with the lattice, particles also suffer incoherent interactions with individual nuclei and may leave their bounded motion, i.e., they de-channel. This latter is the main limiting factor for applications of coherent interactions in crystal-assisted particle steering. We experimentally investigated the nature of dechanneling of 120 GeV/c $e^{-}$ and $e^{+}$ in a bent silicon crystal at H4-SPS external line at CERN. We found out that while channeling efficiency differs significantly for $e^{-}$ ($2pm2$ $%$) and $e^{+}$ ($54pm2$ $%$), their nuclear dechanneling length is comparable, $(0.6pm0.1)$ mm for $e^{-}$ and $(0.7pm0.3)$ mm for $e^{+}$. The experimental proof of the equality of the nuclear dechanneling length for positrons and electrons is interpreted in terms of similar dynamics undergone by the channeled particles in the field of nuclei no matter of their charge.
The usage of a Crystalline Undulator (CU) has been identified as a promising solution for generating powerful and monochromatic $gamma$-rays. A CU was fabricated at SSL through the grooving method, i.e., by the manufacturing of a series of periodical
Numerical simulations and `proof of principle experiments showed clearly the interest of using crystals as photon generators dedicated to intense positron sources for linear colliders. An experimental investigation, using a 10 GeV secondary electron
Charge independence and symmetry are approximate symmetries of nature. The observations of the small symmetry breaking effects and the consequences of those effects are reviewed. The effects of the mass difference between up and down quarks and the o
We show that a contribution due to a second order amplitude with intermediate $bar u d$ in a loop, which was claimed by Descotes-Genon and Kamenik to dominate the CP asymmetry in $b to c ell u$, vanishes.
Recent experimental results for neutron-neutron scattering length are reanalyzed from the point of view of three-nucleon force contribution. We found that the limiting value of $a_{nn}=- 15.8pm 0.5$~fm must be free of any implicit three-body force co